Restructuring Costs - Schedule of Restructuring Costs, Recorded in Restructuring Expense in Condensed Consolidated Statements of Operations, Incurred (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	$ 10,137	$ 12
KFAB Wafer Manufacturing Operations
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	10,137
KFAB Wafer Manufacturing Operations | Early Termination of Supply Contract
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	1,985
KFAB Wafer Manufacturing Operations | Asset Retirement Obligation
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	1,403
KFAB Wafer Manufacturing Operations | Retention Costs
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	3,158
KFAB Wafer Manufacturing Operations | Cost of Equipment Relocation, Shutdown Cost and Other
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	$ 3,591